Centrifugal impeller



United States Patent Office 3,306,529 Patented Feb. 28, 1967 3,306,529 CENTRIFUGAL IMPELLER James K. Nelson, Des Plaines, lll., assignor t Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Filed Nov. 16, 1964, Ser. No. 411,263 7 Claims. (Cl. 230-134) This invention relates to centrifugal impellers, and more particularly to centrifugal impellers or blower wheels of the type commonly used for the translation of air in domestic appliances and the like.

Conventional centrifugal air impellers, or blower wheels, are generally fabricated from steel or like metal, and comprise a hub, blade assembly and solid back plate serving to connect the blade assembly to the hub. In

such assemblies, the back plate exists primarily for structural reasons and contributes little to the air flow.

Improvement of centrifugal impellers of this type, especially in the area of cost reduction, have been limited due to the necessary steps of stamping and assembling the sheet metal parts. In addition, the use of relatively heavy metal components makes it necessary to balance each impeller separately, increasing both the manufacturing time and the cost.

Various attempts have been made to manufacture a low cost centrifugal impeller by fabricating the back plate and blade assembly from a rigid plastic material. These attempts provided a method which has proved successful in the manufacture of lightweight impellers of small diameter, generally four inches and under. However, the method of producing these small assemblies has not proved adaptable to larger impellers due to the relatively thick blades resulting from this method of construction. The impeller assemblies manufactured by the aforementioned method are drawn from the mold in the axial direction, and require a taper of the blades from the end adjacent the back plate to the free end. In large impellers, such construction requires that the blades be abnormally thick at the back plate to provide this taper.

The present invention, therefore, has an object to facilitate the manufacture of centrifugal impeller assemblies.

A further object of the invention is to provide a centrifugal impeller which is lightweight, inexpensive to manufacture, and easily assembled.

A further object of the invention is to provide a method of manufacturing a centrifugal impeller which is easily and inexpensively performed.

The various objects, features and advantages of the invention will appear more fully from the detailed description which follows, taken in connection with the accom panying drawings forming a part of this application, in which:

FIGURE 1 is a plan view showing impeller blading fabricated in accordance with the present invention;

FIG. 2 is an elevational view of the blading of FIG. 1 showing further details of the invention;

FIG. 3 is a front elevational view of a centrifugal impeller showing the blading of FIGS. 1 and 2 assembled in accordance with the present invention; and

FIG. 4 is a vertical sectional view taken along the line IV-IV of FIG. 3 showing the invention in detail.

Referring now to the drawings, especially FIGS. 1 and 2, there is shown an integrally molded blade assembly having a plurality of blades 11, each integrally connected between a pair of substantially parallel side members 12 and 13. Blade assembly 10 is molded in a flat position, as shown in FIG. 2, froma flexible plastic material such as, for example, polypropylene or polystyrene. The blade assembly 10, when so molded, is

drawn from the mold in the short direction of the blades 11, thus permitting the necessary taper while maintaining a relatively thin blade cross-section.

To facilitate fabrication of a plurality of the blade assemblies 10 into a centrifugal impeller assembly, there is provided a air of outwardly extending flanges 14 and 16 each disposed at the outer edge of side strips 12 and 13, respectively At the opposite end of the blade assembly 10, the side members 12 and 13 are provided with a pair of flanges 17 and 18, respectively, and another pair of flanges 19 and 21, similar to flanges 14 and 16, are located at a point substantially mid-way between the two ends of the assembly 10 and adjacent the outer edge of the members 12 and 13, respectively. Each of the flanges 14 and 16, 17 and 18, and 19 and 20 are provided with an opening which may be molded in the flange or drilled after the assembly 10 is removed from the mold, and provides means for fabrication of the blade assembly to the adjacent impeller structure.

Referring now to FIGS. 3 and 4, the invention further provides a hub member 22 having an axial opening 23 suitable for receiving a shaft, and a set screw 24 to facilitate a tight fitting engagement of the hub with the shaft. The hub member 22 is further provide-d with a pair of radially projecting spokes 26 and 27 disposed diametrically opposite one another.

As is best shown in FIG. 4, the spokes 26 and 27 are each provided with an arm 28 and 29, respectively, extending parallel to the axis of rotation of the impeller. In the embodiment shown, the hub 22 is fabricated from a suitable metal, such as steel, and the spokes 26 and 27, and arms 28 and 29, are fabricated from a similar metal wire or rod. The arms 28 and 29 are welded to the hub member as shown, or may be joined by any other suitable method.

Referring again to FIGS. 3 and 4, fabrication of the centrifugal impeller is accomplished by inserting the arm 29 through the openings in flange 19 and flange 21, and simultaneously inserting the arm 28 through the openings in flanges 14 and 17, and flanges 16 and 18. A pair of sheet metal spring clips 31 and 32 of a type well known in the art, are provided at the ends of arms 28 and 29, respectively, to retain the blade assembly 10 on the arms, and restrict movement of the assembly in the axial direction.

In a centrifugal impeller having a blade assembly 10 fabricated from a flexible material such as polypropylene plastic, the blade assembly will hang from the arms 28 and 29 in a configuration unlike that of FIG. 3, with the blade assembly dropping in a non-circular manner from the arms. However, on rotation of the centrifugal impeller about the central axis, the blade assembly 10 assumes a configuration as shown in FIG. 3 due to centrifugal force produced by the rotation.

It should, therefore, be evident from the foregoing description that the present invention provides a centrifugal impeller, which is both inexpensive to manufacture and easy to fabricate.

Further, the novel impeller is of such a relatively lightweight, that once the blade assembly mold is adjusted for nominal balance, there may be no need for the separate balancing of each centrifugal impeller.

In addition, by elimination of the conventional solid back plate usually found in such constructions, a centrifugal impeller is provided which may be mounted with the arms 28 and 29 extending over the motor or drive means, thereby saving space in the final product in which the impeller is to be used.

While the invention has been shown in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible to various changes and modifications without departing from the spirit thereof.

Iclaim as my invention:

A centrifugal impeller suitable for mounting on a shaft comprising: I

a unitary blade assembly of flexible matenal and having a plurality of radially pair of substantially parallel flexible side members and 'plurality of blades each connected between said side members,

hub for connecting said blade assembly to said shaft, and

projecting spokes spaced circumferentially not less than 60 degrees and each having one end disposed on said hub and the opposite end thereof in engagement with said blade assembly,

the engagement of said opposite spoke ends with said blade assembly thereby serving as the only radial support for said assembly, and the flexibility of said blade assembly material being such that the assembly of blades in an annulus assumes a circular form only under the influence of centrifugal forces resulting from rotation of the assembly about the axis of the shaft. The structure of claim 1 in which said flexible material is polypropylene.

A centrifugal impeller suitable for mounting on a shaft, comprising:

a unitary blade assembly of flexible material and having the engagement of said opposite spoke ends with said blade assembly thereby serving as the only radial support for said assembly, and the flexibility of said blade assembly material being such that the assembly of blades in an annulus assumes a circular form only under the influence of centrifugal forces resulting from rotation of the assembly about the axis of the shaft.

A centrifugal impeller suitable for mounting on a shaft, comprising:

a unitary blade assembly of flexible material and having,

pair of substantially parallel flexible side members and plurality of blades each having one end thereof integrally connected to one of said members and the opposite end thereof integrally connected to the other of said members,

hub for connecting said impeller to said shaft, and pair of diametrically opposed radially projecting spokes each having one end thereof disposed on said hub and the opposite end thereof in engagement with said blade assembly,

said pair of spokes thereby serving as the only radial support for said assembly, and the flexibility of said blade assembly material being such that the assembly of blades in an annulus assumes a circular form only 5 under the influence of centrifugal forces resulting from rotation of the assembly about the axis of the shaft.

5. A centrifugal impeller comprising:

an axially disposed hub member,

a plurality of radially projecting spokes each having one end thereof connected to said hub and the opposite end thereof provided with an arm disposed parallel to the axis of rotation of said impeller, and

a one piece blade assembly integrally molded from a flexible material and having :a pair of substantially parallel side members,

a plurality of blades each having one end thereof integrally connected to one of said members and the opposite end thereof integrally connected adjacent the other end of said members,

each of said side members having a plurality of radially projecting flanges disposed thereon and .said flanges each having an opening provided therein for receiving said spoke arms,

:said blade assembly being supported on said hub by the engagement of said arms in said flange openings.

6. A centrifugal impeller comprising,

an axially disposed hub member,

a pair of diametrically opposed radially projecting spokes each having one end thereof connected to said hub, and the opposite end thereof provided with an arm disposed parallel to the axis of rotation of said impeller, and

a one piece blade assembly integrally molded from a flexible material and circumferentially disposed about the axis of said impeller, said assembly having a pair of substantially parallel, side strips of relatively thin radial cross-section,

a plurality of blades each having one end thereof integrally connected to one of said strips and the opposite end thereof integrally connected to the other of said strips,

each of said side strips having a pair of radially projecting flanges formed at opposite edges thereof and disposed in side by side relation in said assembly and a radially projecting flange formed midway between said strip ends,

said flanges each having an opening provided therein for receiving said spoke arms,

said blade assembly being supported on said hub by the engagement of said arms in said flange open- =1I1gS.

7. The structure of claim 6 wherein said flexible mate- 55 rial is polypropylene.

References Cited by the Examiner UNITED STATES PATENTS 2/1958 Busch 230-128 6/1964 Goettl 230l34 

1. A CENTRIFUGAL IMPELLER SUITABLE FOR MOUNTING ON A SHAFT COMPRISING: A UNITARY BLADE ASSEMBLY OF FLEXIBLE MATERIAL AND HAVING A PAIR OF SUBSTANTIALLY PARALLEL FLEXIBLE SIDE MEMBERS AND A PLURALITY OF BLADES EACH CONNECTED BETWEEN SAID SIDE MEMBERS, A HUB FOR CONNECTING SAID BLADE ASSEMBLY TO SAID SHAFT, AND A PLURALITY OF RADIALLY PROJECTING SPOKES SPACED CIRCUMFERENTIALLY NOT LESS THAN 60 DEGREES AND EACH HAVING ONE END DISPOSED ON SAID HUB AND THE OPPOSITE END THEREOF IN ENGAGEMENT WITH SAID BLADE ASSEMBLY, THE ENGAGEMENT OF SAID OPPOSITE SPOKE ENDS WITH SAID BLADE ASSEMBLY THEREBY SERVING AS THE ONLY RADIAL SUPPORT FOR SAID ASSEMBLY, AND THE FLEXIBILITY OF SAID BLADE ASSEMBLY MATERIAL BEING SUCH THAT THE ASSEMBLY OF BLADES IN AN ANNULUS ASSUMES A CIRCULAR FORM ONLY UNDER THE INFLUENCE OF CENTRIFUGAL FORCES RESULTING FROM ROTATION OF THE ASSEMBLY ABOUT THE AXIS OF THE SHAFT. 